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Discussion Starter · #1 ·
2011 naked R, I'm getting a "LAMP" warning light in my instrument cluster. Hooked up the GS-911 and got the fault code "Rear Lamp open-circuit". I dug through the wiring for at the rear lamp
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and as you can see it's a nest of snakes. I've checked 100% of the connections pictured and re-assembled, reset the fault codes via the GS-911 and I'm still getting the LAMP fault code on the dash and GS-911.
Next I pulled out the multimeter and tested the connections to the bulb housing which has 3 male spade connectors: Positive, Negative and Brake. When I check P to N at the bulb I get erratic readings ranging from 1.xx-10-xx and it's never steady, the gauge just bounces with different readings, I got the same erratic readings using the N on the battery. When I connect to P on the meter to the Brake connection I get a steady reading of 2.77 or thereabouts, when I apply the brake the light increases in brightness (2nd filament) and the meter reads 11.xx steady. WTF is going on????????
I assume a steady reading as I'm getting off the Brake connection is good and the erratic readings on the Positive post is my problem area. I've checked and reconnected ALL the Posi-Connectors pictured, checked the wiring to the Skene secondary lights mounted on the license plate box, everything appears tight, clean and well connected. Shouldn't I be getting a steady reading on the Positive feed as I get on the Brake feed? And where do I go from here to figure out where the hiccup is that's causing the LAMP light?
Any and all suggestions welcome even if just another sarcastic one.
TIA
 

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Well, that's a bit of a rat's nest, isn't it?

You clearly don't have a good circuit on the rear light. Your brake light is a separate positive wire activated by either of the brake switches. So, since the brake light works, you likely have a bad positive wire connection. You're using lots of posi-connectors and some crimp splices. Not automatically bad, but maybe you need to re-lay new circuits?

I only used 3 posi-connectors in my setup. One attaches to the positive for the brake light as a SIGNAL wire for the P3 and Photon Blaster. Another attaches to the rear light as a SIGNAL wire for my power distribution block to tell it when to turn on switched power circuits. I used a 3rd (not pictured) to attach two ground wires from the Photon Blaster into one of the ground wires of the P3 because I couldn't cram 5 wires into the negative terminal block.

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I do use crimp splicers when needed since it's safer (for me) than trying to solder wire on the bike, but I always use heatshrink over the connection to seal it from water and debris intrusion. So, if there's a crimp splice on that positive wire, maybe one's gone bad? ALL ACCESSORIES run to a power distribution block connected directly to the battery. Traditional 12 volt or CANBUS, it's easier and safer than tapping into existing circuits for power.
 
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Mark – 2015 R1200R-LC Exclusive
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My first question would be why all those wires are there. Has a brake or tail light modulator been inserted into the circuit? That would explain erratic voltage readings at the bulb.

As ZNG suggests, I'd be redoing all that wiring to a tidy installation (even if it did work!). But in the meantime, have you checked the tail/brake light bulb for continuity across each filament?
 
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Discussion Starter · #4 ·
Why all those wires? necessary for the Skene P3 w/turn signal. Here's the wiring diagram:
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and they've worked flawlessly since install fall of '16, and they work now. I've gone through all the Posi-Connections and they're all tight and good (though unsightly for sure).
I just replaced the clutch disk which involves splitting the rear frame from the engine and the wiring harness had to be released from the frame and snaked through to the front of the bike to facilitate the disk install.

I'm getting a wonko reading on the volt meter only when I test the Positive lead to the tail light bulb, it's erratic as stated earlier. the Brake light has a separate lead which reads a steady 11.xx when the brake is applied. Ergo as ZNG sez the problem is with the positive wire connection to the brake light. I cut it back a couple of inches and crimped a new female connector. I'm wondering if the bulb holder itself is at fault as it may have gotten damaged when dragged thru the frame to the front for frame removal. Is there a way to test the bulb holder?
 

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Mark – 2015 R1200R-LC Exclusive
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Why all those wires? necessary for the Skene P3 w/turn signal
Ah, a subtlety not disclosed in the original post.

I’ll leave it to those who speak Skene.
 

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I'm wondering if the bulb holder itself is at fault as it may have gotten damaged when dragged thru the frame to the front for frame removal. Is there a way to test the bulb holder?
Well, my RS is a 2018 model. The tail light comes off, and the bulb socket goes with it once you disconnect the harness. I’m not sure why the bulb holder would get dragged through anything.

I doubt testing the bulb holder will matter. Test the bulb. Find something to hold it steady and multimeter its contacts. Being dual-filament, I presume there’s two points on the bottom for two separate positive feeds and the outer rim is negative. Do you get steady continuity both ways? If yes, fault is on the positive feed for the rear lamp. If no, you have a failing bulb. The filament may be detached but works whenever it happens to make contact to a ground in the bulb. You can double check good continuity by doing the same with a 12 volt source to ensure the bulb lights up. If it consistently flickers on either after several attempts, you have a bad bulb.

Or, if you happen to have the right type bulb lying around, try a different bulb.

* * *

NOW, if you want to test the positive wire to the bulb socket, that can be tricky. If you have a sewing needle (very fine point), gently pierce the wire insulation near the socket and read voltage there. If steady, test within the socket. If it fluctuates, the connection is damaged.

Again, I’d expect the bulb socket to be wireless...a direct plug to the harness, but that may be what they did on newer models. If indeed you mean to say your wires terminate in the plug connector, you could have corroded, bent, dirty or damaged power leads. This is usually fixed with cleaning or gentle realignment with small tools. Check both sides as it could be in the male or female side.

Let us know what you find.
 

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Discussion Starter · #7 ·
Cannot compare '18 model to '11, two entirely different animals with many many changes made. 05 - 13 vintage require splitting the frame to access the clutch etc 10 hrs shop time for the job. Shops quote $1600 minimum with most clutch jobs coming in around $2000-$2500. Here's the steps to access: http://www.tonydmarketingwizard.com/scoot/images/Manual_ToDo_List.PNG

The male spade connections on the bulb holder is where I'm taking the readings. The P contact is where I'm getting the erratic readings. I'm ordering a bulb holder today: $13, having 'em include a bulb for chuckles and grins.
 

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For $13 you'd think they'd include the bulb. ;)
 

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Discussion Starter · #9 ·
I ordered a half a dozen fillister screws at the same time: $2.50 each
 
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